Papermakers&#39; felts and like industrial woven textile fabrics



PAPERMAKERS FELTS AND `LIKE INDUSTRIAL WOVEN TEXTILE FABRICS Thomas I-Iindle, Sam Lord, and Edward Race, Blackburn,

England, assignors to Scapa Dryers Limited, Black- Ibin-n, England, a corporation of England Filed Aug. 15, 1956, Ser. No. 604,278

Claims priority, application Great Britain Sept. 23, 19'55 15 Claims. (Cl. 139-426) This invention relates to Woven textile fabrics for industrial uses and is particularly concerned with those endless woven bands vwhich Iare termed paperm-akers dryer fel which, in papermaking, are used to carry the sheet or web of paper in close contact with the drying cylinders of the paper machine. Y

In the early days of papermaking by machinery, the dryer felts were actually of wool and were subjected to a fulling operation such as is customary in the manufacture of true woven felts, so that the term felt as applied to these earlier drying felts was doubtless `justifiable. It is because of certain peculiarities of both surface and internal structure that wool is susceptible to felting, Whereas smooth-surfaced fibers of vegetable origin, for instance cotton; bers of mineral origin, for example asbestos; and synthetic fibers produced by extrusion, for example Dacron (which chemically speaking is polyethylene terephthalate) cannot be felted. As coni trasted with wool and to distinguish therefrom, these smooth-surfaced fibers are herein referred to under th general term non-felting fibrous material.

As the ant of p-apermaking progressed, the Vwool felts were superseded by cotton felts, and since cotton is not susceptible to felting, the term felt as applied to these Woven cotton bands was really a misnomer, although its use as applied to these dryer bands has persisted. At a still later stage in the development of the papermaking art, felts of cotton combined with asbestos were introduced, and felts of this type, as well as'those wholly of cotton, are commonly employed at the present time.

Since a function of the dryer felt is to assist in the drying of the paper web by absorbing moisture from the latter, Vit is essential that the pores or interstices of the felt be kept open for the absorption and passage of moisture. However, in practice it is found that the felt, particularly that face of the felt which contacts the paper web, becomes blocked with insoluble matter such as pitch,

resistance to dry heat and to attack by dilute acids at high temperature.

A felt in which filamentous synthetic yarn, constituting from 6% to 14% of the total weight of the felt, and wherein the synthetic yarn is incorporated as a helical wrapping about a core of another material, for example cotton, is disclosed in the United States patent to Hindle et al., No. 2,882,933, dated April 2l, 1959, and which issued on application-Serial No. 524, 410, filed July 26,

1955 and copending with the present application.

However, it has been observed that such felts comprising substantial proportions of these synthetic yarns tend to lill up with foreign material even more rapidly than the older felts of cotton or cotton and asbestos. In searching for a reason for this phenomenon it was noted that the synthetic fibers such as nylon or Dacron (which do not readily absorb moisture), generate and hold very high electrostatic charges when exposed to friction. While it would not appear reasonable to think that such electrostatic charges would develop in a dryer felt contacting a wet paper web and running inV an atmosphere filled with moisture, tests have shown that such electrostatic charges are actually built up on felts while in operation, 'and particularly felts containing substantial cellulose fibers, china clay and other materials present in the stock from which the paper web is made,`or in the atmosphere surrounding the papermaking machine, and as the dryer felt thus becomes progressively less permeable to water, water vapor and air, the drying efficiency of the felt may be seriously impaired long before it is actually worn out. Under some circumstances, the collection of this extraneous matter on the face of the felt may become so great as to produce undesirable marks on or even to rupture the impressionable paper web. Thus, the problem of dirt collection on and in dryer felts is serious. Y Y

Recently, the employment of some of the synthetic fibers, for instance nylon or Dacron, in the manufacture of dryer felts has been suggested, and felts comprising such materials in substantial percentages have been made and are in actual use. The initial cost of an all-Dacron dryer felt is relatively high, but in many cases this Vis justified by the greatly increased service life which results percentages of 'the synthetic fibers. As a result of such tests, it has seemed possible Vthat the plugging up of dryer felts with foreign material may be due, in part at least, to electrostatic action, and extensive tests have resulted in the surprising discovery, arising from experiments in making felts from mixtures of different fibers, that felts made from different mixtures notvonly generate different degrees of electrostatic charge, but also different properties as regards the collection or non-collection of dust. The present invention is based upon the conception that the collection of dirt and foreign matter on and in such dryer felts is due to a substantial degree to the presence of static electrical charges and that by the employment, inthe manufacture of such felts, of fibers having different electrostatic properties in proper proportions, there will result a felt having the property of remaining cleaner throughout its service life than any ofthe felts which have heretoforeV been employed.

According Ito the present invention, there is provided tion of an electrostatic charge is substantially reducedV or eliminated in the manufactured fabric, and then weaving the fabric from said selected fibers. p

Another object of the present invention is the provision of a papermakers dryer felt as aforesaid, characterized in that the selected fibers are cotton and Dacron constructed with the Dacron in close contact with the cotton,

Another object of the present invention is .to provide a papermakers dryer felt characterized in that the selected fibers are nylon and Dacron constructed with the Dacron in close Contact with the nylon.

Another object of the present invention is to provide' a papermakers dryer felt characterized inthat the selected fibers are cotton, nylon and Dacron so `arranged that'each of fthe -three kinds of fiber is in close contact with the other two. i

' Another object of the present invention is to provide U a papemiakers dryer felt in which Orlon is substituted for at least part of the Dacron. Orlon is the trade name applied to polyacrylonitrile fiber.

Another object of the present invention is to provide a papermakers diyer felt in which asbestos ber is substituted for at least part of the cotton.

The extent to which dryer felts manufactured in accordance with the present invention keep themselves clean during their life on the paper machine compared with dryer felts composed wholly of cotton or wholly of Daeron or wholly of nylon is most surprising.

It is believed that the chief factor of dirt repulsion or non-accumulation, giving the aforesaid new characteristic, is a function of the generation, and/or discharge of electrostatic charges on the electrostatically different fibers of the various components of the felt, on the fibers of the paper web and on the various components of lthe paper stock which comprise the dirt. It is well known that when two materials such as silk and acetate rayon are rubbed together, one becomes positively charged and the other negatively charged and that different materials share this characteristic in different degrees. Let the positively charged material be called P and the negatively charged material be called N. If four different materials, A, B, C and D, are now tested against both P and N, it may be found that A becomes positive to both P and N, that B becomes negative to both P and N, or that C becomes negative to P and positive to N. What will not occur is that D will become positive to P and negative to N. It is, indeed, possible to arrange materials in a vertical series or list in which any material rubbed against another lower on the list will acquire a positive charge and rubbed against another higher on the list will acquire a negative charge.

Such list is hereinafter termed the electrostatic series, an example of which is as follows:

(+) Ramie Glass Vulcanized Rubber Nylon Cellulose Acetate Wool Orlon Silk Daeron Viscose Polyethylene Cotton As a result of research, the conclusion has been reached that the dirtying of a dryer felt composed of only one type of fiber, or composed of two types of fibers relatively close together in the electrostatic series, is due in no small degree to. the accumulation of an electrostatic charge on the fibers of the felt, with consequent attraction between the charged fibers and the uneharged or oppositely charged components of the paper web. Having been brought into contact by electrostatic attraction, the extraneous matter adheres to the bers of the felt by mechanical forces and by occlusion in pits and crevices of the fabric surface.

However, it has further been found that by the correct choice of fiber components and their proportions in a dryer felt according to the electrostatic series, both as regards the fibers of the felt and of the paper, it is possible to attain a state of, or approaching electrostatic neutrality in the system appertaining at that part of the papermachine clothed by dryer felts.

In such a complex system as that presented at the drying section of a paper-machine, it is obviously irnpossible to predict the electrical charges which will be acquired by all of the many components present, and, therefore, equally impossible to predict the nature and proportions of the components necessary in a dryer felt to give maximum repulsion or non-attraction of those components of the paper stock which tend to deposit as dirt on the dryer felt.

From the results we have obtained, it is apparent that the nature and proportions of the components of dryer felts manufactured in accordance with the present invention are dependent upon a number of factors, chief among which are (a) the temperature of the system at the drying section of the paper-machine; (b) the humidity of the system at the drying end of the paper-machine; (c) the composition of the paper furnish; (d) the pH value of the paper web. Since these factors have different values on different paper-machines, and even on different sections of the same machine, it follows that, in fulfilling the objects of this invention, relatively wide variations in the proportions of the different fibrous ingredients of the dryer felts are possible. Under any given set of conditions on any drying section of a papermachine, there are optima in the proportion of Daeron, cotton and/or nylon, but these optima vary with varying conditions.

It has been found that dryer felts having the following compositions exhibit greatly improved cleanliness:

(a) 25% to 75% by weight of Daeron and 75% to 25% by weight of cotton;

(b) 25% to 75% by weight of Daeron and 75% to 25% by weight of nylon;

(c) 2% to 75% by weight of Daeron, 2% to 20% by weight of nylon and 96% to 20% by weight of cotton, and

(d) felts composed as in (a) or (c) above but in which the cotton is partially or wholly replaced by asbestos.

Dryer felts having the aforesaid compositions achieve the object of keeping themselves cleaner during service use than felts composed wholly of cotton or of Daeron or of nylon.

In our invention, the nylon and Daeron may conveniently be present in the dryer felt as continuous lilament yarn, as staple fiber carded and spun into yarn, as yarn spun directly from a continuous filament tow or as a blend with cotton, the blended mixture being carded and spun into yarn. When, herein, fibrous material is referred to, the term fibrous is to be understood as inclusive of any of the materials employed in the manufacture of yarns, whether as short bers or long filaments, and whether of organic or inorganic materials, and whether synthetic or of natural origin.

In the accompanying drawings,

Figs. l, 2, 3 and 4 are conventional longitudinal Weave structure cross-sections through a straight weft showing several examples of a suitable weave for a papermakers dryer felt made in accordance with the present invention, a single repeat of the weave being indicated by cross-section lines on the weft.

The following are examples of felts, which, on particular sections of particular paper-machines, possess the ability of keeping cleaner throughout their service lives than similar felts constructed wholly of one type of ber:

Example 1 The weave structure of the dryer felt shown in Fig. l is used. In the diagram, the working face of the felt is at A and the back at B. The warp yarns 1, 2 and 3, which appear on the face of the fabric, are composed of 14s/9 cotton. Each of the weft threads, a, b, c, d is composed of three yarns of 7s cotton plied with one yarn of 6s spun Daeron. There are 68 warp threads per inch and 56 weft threads per inch in the finished dryer felt. Such a felt is composed of 33.9% by Weight of Daeron and 66.1% by weight of cotton. In service on a particular section of a particular paper machine, a felt manufactured in the above construction kept very much cleaner throughout its life than did similar felts constructed wholly of cotton or wholly of Daeron.

Example 2 The weave structure of the dryer felt, shown in Fig. 1 is used. Each of the warp yarns `1, 2, 3, 4 and 5 is composed of 6s/ 5 spun Daeron, and each of the warp yarns 6, 7 and 8 is composed of 14s/9 cotton. Each of the weft threads is composed of two yarns of 7S cotton plied Example 3 The weave structure of the dryer feltshown'in Fig. 2 is used. Each of the warp yarns 1 to 8 inclusive,y is

composed of eight strands of4 14s cotton plied with two nylon filament yarns each of 210 total denier (for example, 35 filaments of nylon each of-'6 denier). Each of the weft yarns a, b is composed of nine strands of 7s cotton plied with two Daeron lfilament yarns each of 2150 total denier (for example 50 filaments of Daeron eaehof 5 v denier). There are 63 Warp threads Vper inch and 27 weft threads per inch in the finished dryer felt. Such a felt is. vcomposed of 90.4% by weight of cotton, 6.4% by Weight of nylon, and 3.2% by weight of Daeron."

Example 4 The Weave structure of the dryer felt, shown in Fig. 2 is used. Eachof the'warp yarns 1 to K8 inclusive, is composed of eight strands of 14s cotton plied with one nylon filament yarn of 210 total denier, Each of the weft yarns a, b is composed of nineV strands of 7s cotton plied with one nylon filament yarn of 210 total denier and one Dacron filament yarn of 250 total denier. There are 63 warp threads per inch and 27 weft threads per inch in the finished felt. Such a felt is composed of 90.1% by weight of cotton, 4.5% by Weight of nylon and 5.4% by weight of Daeron.

Example 5 The weave structure of the dryer felt shown in Fig. 3 is used. The Warp yarns 1, 2 and .3, which appear on the face of the fabric, are each composed of 6s/4 spun Daeron, and the warp yarns 4, 5, 6, 7 and 8 are each composed of five strands of 7s cotton plied with two nylon filament yarns earch of 210 total denier (for example, 35 filaments of nylon each of 6 denier). Each of the weft yarns a, b, c is composed of five strands of 7s cotton plied with two nylon filament yarns each of 210 total denier.

vThere are 68 warp threads per inch and 48 weft threads per inch in the finished felt. Such a dryer felt is composed of 19.1% by weight of Daeron, -8;1% by weight of nylon, and 72.8% by weight of cotton.

Example 6 The weave structure ofthe dryer felt, shown in Fig. 3

is used. The construction of the Warp of the dryer felt is the same as that of Example 5. Each of the weft yarns a, b, c is composed of five strands of 7s cotton plied wit-h -two Daeron filament yarns each of 250 total denier.

There are 68 Warp threads per inch and 46 weft threads per inch in the finished dryer felt which is thus composed of 24.3% by weight of Daeron, 3.8% by weight of nylon Yand 771.9% by Weight ofV cotton.Y

Example 7 'I'he weave structure used is as shown in Fig. 3, and the composition of the warps 11 to `8 inclusive, of the dryer felt are the same as thoseof Example 5. `Each of the weft yarns a, b, c is composed of five strands of 7s cotton plied with one nylon filament yarn of 210 total denier and one Daeron filament yarn of 250 total denier. There are 68 Warp threads per inch and 47 weft threads per inch in the finished dryer felt which is thus composed of .7% by weight of Daeron, 5.9% by Weight of nylon and 2.4% by weight of cotton.

Example -8 yThe Weave structure of the dryer felt shown in Fig. 3

.y is used. v Each of the Warp yarns 1, 2 and 3 is composed f of 6s/ 4 spun Daeron. A blend of 90% cotton and 10% nylon'ber is carded and spun to a count of 7s. Each of the warp yarnsv 4, 5, 6, 7 and 8 and each of the weft A e yarns a, b, c is composed of this V7s cotton-nylon plied 5- fold; There are 68 warp threads per inch and 48 weft threads per inch in the finished felt. Such a felt iscomposed of 21.2% by weight of Daeron, 6.5% by weight of nylon and 72.3% by weight of cotton.

VExampley l9 The Weave structure is'as shown in Fig. 3 and the compositionof the warps `1 to 8 inclusive, of the dryer felt is p Example The weave structure o f the dryer felt shown in Fig. 1 is used. Each lof the warp yarns 1, 2, 3, 4 and 5 is 'composed lof 6s/4 spun Daeron and each of the warp yarns6, 7 and 8 is composed of eight strands of 14s cotton plied with two nylon filament yarns each of 210 total denier. Each weft yarn a, b, c, d is composed of live strands of 7s cotton plied with one Daeron filament yarn of 250 total denier. There are y68 warp threads per inch and 56 weftpthr'eads per` inchV in the finished dryer felt.

`Such a felt is composed of 35.4% by weight of Daeron, 2.3% by weight of nylon and 62.3% by weight of cotton.

Example 11 The Weave structure isv as shown in Fig. 1 and the composition of the warps 1 to 8 inclusive, of the dryer felt is the same as those of Example 10. Each weft yarn a, b, c, d is composed of five strands of 7s cotton plied With one Daeron filament yarn of 250 total denier and one nylon filament yarn of 210 total denier. There are v68 Warp threads per inch and 56 weft threads per inch in the finished felt. ySuch a felt is composed of 34.5% by weight of Daeron, 4.7% by weight of nylon and 60.8% by Weight cotton.

Example 12 The weave structure is as shown in'Fig. 1 and the composition of the warps y1 to 8 inclusive, of the dryer felt is the same as those of Example 10. Each weft yarn a, b, c, d is composed of five strands of 8s cotton plied with one Daeron filament yarn of 250 total denier and two nylon filament yarns of 2'10 total denier. There are 68 warp threads per inch and 5 6 weft threads per inch in the finished dryer felt. Such a felt is composed of 35.6% by Weight of Daeron, 7.4% by weight of nylon and 57.0% by weight of cotton.

Example 13 The Weave structure of the dryer felt shown in Fig. 2

is used. Each of the warp yarns 1, 2, '3, 4 and 5 is com- Y posed of 6s/4 spun Daeron and each of the warp yarns W6, 7 and 8 is composed of eight strands of 14s cotton plied with two nylon filament yarns each of 2.10 total denier. Each weft thread a, b is composed of eight strands of 7s cotton plied with one Daeron filament yarn of 250 total denier and two nylon filament yarns each of `210 total denier. There are 63 warp threads per inch and 27 weft threads per inch in the finished felt. Such a felt is composed of 36.3% by weight of Daeron, 5.3% by weight of nylon and 58.4% by weight `of cotton.

Example I4 of seven strands of 15s cotton plied with neDacr filament yarn of 250 total denier and one nylon filament yarn of 210 total denier. There are 67'warp threads per inch and 50 weft threads per inch in the finished dryer felt. Such a felt is composed of 43.4% by weight of Daeron, 2.8% by weight of nylon and 53.8% by weight of cotton.

Example 15 The weave structure shown in Fig. 1 is used and the composition of the warps 1 to 8 inclusive, of the dryer felt is the same as that of Example 10. Each of the weft yarns ais composed of 6s/ 5 spun Daeron and each of the weft yarns b, c and d is composed of six strands of 8s cotton plied with two nylon filament yarns each of 210 total denier. There are 68 warp threads per inch and 56 weft threads per inch in the finished dryer felt. Such a felt is composed of 43.8% by weight of Daeron, 5.8% by weight of nylon and 50.4% by weight of cotton.

Example 16 The weave structure shown in Fig. 2 is used and the composition of the warps 1 to 8 inclusive, of the dryer felt is the same as that of Example 13. Each of the weft threads a is composed of 7s/9 spun Daeron and each of the weft threads b is composed of eight strands of 7s cotton plied with two nylon filament yarns each of 210 total denier. There are 64 warp threads per inch and 27 weft threads per inch in the Ifinished dryer felt. Such a felt is composed of 57.7% by weight of Daeron, 3.9% by weight of nylon and 38.4% by weight of cotton.

Example 17 The weave structure shown in Fig. 3 is used and the composition of the warps 1 to 8 inclusive, of the dryer felt is the same as that of Example 14. Each of the weft threads a is composed of 7s/ 4 spun Daeron and each of the weft threads b and c is composed of seven strands of `15s cotton plied with two nylon filament yarns each of 210 total denier. There are 67 warp threads per inch and 50 weft threads per inch in the finished dryer felt. Such a felt is composed of 52.0% by weight of Daeron, 6.4% by weight of nylon and 41.6% by weight of cotton.

Example 18 The weave structure of the dryer felt shown in Fig. 4 is used. Each of the warp yarns 1, 2, 3, 4, 5 and 6 and each of the face weft yarns a are composed of 6s/41 spun Daeron. Each of the warp yarns 7, 8, 9, 10, 11 and 12 and each of the weft yarns b and c are composed of eight strands of 15s cotton plied with two nylon filament yarns each of 210 total denier. There are 48 warp threads per inch and 64 weft threads per inch in the finished felt. A `dryer felt of this construction, which has a completely weft-hushed face, is composed of 52.1% by weight of Daeron, 6.2% by weight of nylon and 41.7% by weight of cotton.

Example 19 The weave structure of the dryer felt is the same as that of Example 18 as shown in Fig. 4. Each of the warp yarns -1 to 12 inclusive, and each of the face weft yarns a are composed of 6s/4 spun Daeron. Each of weft yarns b and c is composed of eight strands of 15s cotton plied with two nylon filament yarns each of 210 total denier. There are 48 warp threads per inch and 68 weft threads per inch in the finished felt. A dryer felt of this construction is composed of 72.4% by weight of Daeron, 3.6% by weight of nylon and 24.0% by weight of cotton.

Example 20 The weave structure of the dryer felt is the same as nylon filament yarns each of 210 total denier. Each of the face weft yarns a is composed of asbestos, spun round a core of 6s spun nylon to a resultant count of 0.8s.` Each of the weft yarns b and c is composed of eight strands of 15s cotton plied with two nylon filament yarns each of 210 total denier. There are 46 warp threads per inch and 62 weft threads per inch in the finished felt. A dryer felt of this construction is composed of 17.7% by weight of Daeron, 8.4% by weight of nylon, 36.6% by weight of cotton and 37.3% by weight of asbestos.

Example 21 The weave structure of the dryer felt is the same as that of Example 18 as shown in Fig. 4. Each of the warp yarns is composed of 6s/4 spun Daeron. Each of the face weft yarns a is composed of asbestos, spun round a core of 6s spun nylon to a resultant count of 0.8s. Each of the weft yarns b and cis composed of eight strands of 15s cotton plied with two nylon filament yarns each of 2.10 total denier. There are 48 warp threads per inch and 62 weft threads per inch in the finished felt. A dryer felt of this construction is composed of 35.7% by weight of Daeron, 8.5% by weight of nylon, 18.4% by weight of cotton, and 37.4% by weight of asbestos.

Example 22 The weave structure of the dryer felt is the same as that of Example 1 as shown in Fig. 1. A blend of 90% cotton and 10% nylon is carded and spun to a count of 14s. Each warp yarn 4 to 8 inclusive, is composed of this 14s cotton-nylon plied 9-fold. Each weft yarn a, b, c, d is composed of eight strands of 15s cotton plied with one Daeron filament yarn of 250 total denier. There are 70 warp threads per inch and 54 weft threads per inch in the finished felt. Such a felt is composed of 3.3% by weight of Daeron, 5.9% by weight of nylon and 90.8% by weight of cotton.

Example 23 The weave structure of the dryer felt is the same as that of Example 3 as shown in Fig. 2, and the warp yarns are of the same composition as those of Example 22. Each weft yarn a, b is composed of seven strands of 7s cotton plied with two Daeron filament yarns each of 250 total denier. There are 63 warp threads per inch and 27 weft threads per inch in the nshed felt. Such a felt is composed of 3.6% by weight of Daeron, 5.8% by weight of nylon and 90.6% by weight of cotton.

Example 24 The weave structure of the dryer felt is the same as that of Example 5 as shown in Fig. 3, and the warp yarns 1 to 8 inclusive, are of the same composition as those of Example 22. Each weft yarn a, b, c is composed of six strands of 7s cotton plied with two Daeron filament yarns each of 250 total denier. There are 68 Warp threads per inch and 46 weft threads per inch in the finished felt. Such a felt is composed of 5.0% by weight of Daeron, 5.0% by weight of nylon and 90.0% by weight of cotton.

Example 25 Equal weights of Daeron staple fiber and nylon staple fiber are blended, carded, and spun to a count of 6s. Both warp and weft yarns of the dryer felt, the weave structure of which may be that yof Example 1 (Fig. 1), Example 3 (Fig. 2), or Example 5 (Fig. 3) are composed of the above 6s blended yarn plied 4-fold.

Example 26 The weave structure of the dryer felt may be the same as that of Example 1 (Fig. 1), Example 3 (Fig. 2), or Example 5 (Fig. 3). Warp and weft yarns are all composed of two strands of 6s spun Daeron, plied with two strands of 6s spun nylon. Dryer felts constructed in ae- Y 9 eordance with Examples 25 and 26 are composed of 50% by weight of Daeron and 50% by weight of nylon.

Example 27 The weave structure of the dryer felt may be that of Example 1 (Fig. l), Example 3 (Fig. 2) or Example 5 (Fig. 3). Each Warp yarn is composed of 6s/4 spun Daeron and each weft yarn of 6s/4 spun nylon. Such a dryer felt, when of the Weave structure shown in Fig. 1, is composed of 54.8% by weight of Daeron and 45.2% by weight `of nylon; Awhen of the Weave structure shown in Fig. 2, the dryer felt is composed of 70% by weight of Daeron and 30% byrweight of nylon; and when of the weave structure shown in Fig. 3, the dryer felt is i composed of 58.6% by weight of Daeron and 41.4% by weight of nylon.

It is to be understood that our invention is not limited to the above examples. The dryer felts employed on a paper-machine vary considerably in weight per -unit area, weave structure, counts of yarn and other factors, the nature of the felt being dependent upon the type and structure of the paper-machine, upon the type of paper manufactured, and upon conditions of temperature and humidity appertaining at that drying section of the papermachine which the felt clothes. Consequently, it is possible to define all the types and structures of the fabrics to which this invention relates. It is to be understood, however, that yar-ns of the quality, counts, twist and the like would be used to produce a dryer felt according to the invention `as have normally been used hitherto, and that papermakers dryer felts of the quality, Weave, structure, weight per unit area, threads per inch and the like as have hitherto been manufactured for use on a papermachine, can be produced in accordance with the invention, such dryer felts being constructed of Daeron, cotton and/ or asbestos, and/ or nylon, in such a manner that any one material is in close contact with the other materials.

In the normal production of paper, during its passage through the drying sections of a paper-machine, the web of paper -acquires a high electrostatic charge. On fastrunning machines, this static electricity is so troublesome that its Idischarge through earthed copper wires is essential. From theoretical considerations, it appears probable that if all the drying sections or even those drying sections nearest to the reel-up of the paper-machine were clothed with dryer felts constructed in accordance with this invention, the electrostatic charge on the paper web would be lmuch less than when the drying sections are clothed with felts of the type hitherto manufactured.

EIt is obvious that the principle of the invention is one which is not confined to the dryer felts used on papermachines. There are many instances in which the use of fabrics for industrial purposes results tin the production of undesirable electrostatic charges, and it is believed `that fabrics constructed in accordance with the present invention, `because of their ability to eliminate, reduce or, in certain cases, reverse the polarity of the electrostatic ctharges which tends -to accumulate when the fabrics rub against other materials, will find useful applications in many spheres in which fabrics are used industrially. For example, the fabrics which clothe the laundry machines which dry and press laundered textiles were formerly made of wool or cotton. Recently, laundry cloths constructed Wholly of Daeron have been introduced, but the expected advantages of the Daeron fabrics have been olfset by the disadvantages resulting from the accumulation of electrostatic charges which attend their use. It is belived that a laundry cloth constructed in accordance with the present invention, while retaining the desirable features of a wholly Daeron fabric, will be free from the defect of producing high electrostatic charges in itself and in the materials with which it comes into intimate contact.

As a further example of the application of the present A` '10 invention, synthetic bers are beingused in the' manufacture of filter fabrics andbags which are employed in the filtration of dry materials, for example, in dust extraction apparatus. It is contemplated that such filter fabrics and bags, constructed'in ,accordance with the present ifnv'ention, will exhibit less tendency to become ineffective due to the blocking of fiber interstices by dust particles than thesfabricsrand bags now constructed of only one type of ber.

We claim:

1. A paperrnalrersV dryer felt consisting of non-felting fibrous material, Va portion ofmsaid fibrous material being Daeron Which'is electro-negative as compared with cotton, and `another"portieriof said fibrous material being nylon which is electro-positive as compared with cotton, the relative proportions of the Daeron and nylon being such as to render the felt, as a Whole, substantially neutral electrostatically, the Daeron constituting from 3.6% -to 72% of the total weight of the felt, and the nylon constituting from 3% to 50% of the total weight of the felt.

2. A papermakers dryer felt, according to claim 1, wherein Daeron constitutes at least 3.2% and nylon constitutes at least 2.3% of the total Weight of the felt.

3. A papermakers dryer felt, according to claim l, wherein the total amount of Daeron and nylon combined constitutes at least 50% by weight of the felt.

4. A papermakers dryer felt, according to claim 1, wherein the total amount of Daeron and nylon combined constitutes at least 75% of the total Weight of the felt.

5. A papermakers dryer felt, according to claim 1, wherein the felt consists solely of Daeron and nylon in equal proportions by weight.

6. A papermakers dryer felt, according to claim 1, wherein Daeron and nylon constitute the entire felt, the proportion of Daeron to nylon being of the order of 72% to 28%.

7. A papermakers dryer felt, yaccording to claim 1, wherein the felt comprises a natural fibrous material in addition to the Daeron and nylon.

8. A papermakers dryer felt, according to claim 1, wherein the felt comprises cotton n addition to Daeron and nylon.

9. A papermakers dryer felt consisting of interwoven warp and weft yarns, certain at least of said yarns comprising Daeron which, under the conditions of use of such a dryer felt, -tends to accumulate a negative electrostatic charge, and certain at least of said yarns comprising nylon which, under the conditions of use of such a felt, is electro-positive relatively to Daeron, the Daeron and nylon being disposed in electrical conducting relation within the felt and being in such relative proportions that they electrically neutralize each other so that the felt, as a whole, does not tend to accumulate foreign material by electrostatic attraction.Y

l0. A papermakers -dryer felt, according to claim 9, further characterized that in certain at least of said yarns both Daeron and nylon are incorporated.

11. A papermakers dryer felt, according to claim 9,

further characterized in that certain at least of the warp yarns consist of Daeron and nylon in contact with each other.

12. A papermakers dryer felt, according to claim 9, wherein certain at least of the yarns consist of a blend of Daeron and nylon alone.

13. A papermakers dryer felt, according to claim 9,

further characterized in that certain at least of the yarns consist only of Daeron.

14. A papermakers dryer felt, according .to claim 9,

further characterized in that certain at least of the yarns comprise Daeron, cotton and nylon spun together.

15. A woven fabric which, if subjected to friction during use, remains substantially neutral electrostatically,

said fabric comprising fibrous textile material spun into yarns, some of the fibrous material being Daeron Y References Cited in the file of this patentV 10 UNITED STATES PATENTS 2,506,667 Hall May 9, 1950 2,540,874 Geddings Feb. 6, 1951 2,542,297 Sunbury et al. Feb. 20, 1951 15 12 Hebeler July 29, 1952 Skeer et al. June 5, 1956 Hindle et al. Apr. 2l, 1959 FOREIGN PATENTS Australia Apr. 3, 1947 Great Britain Oct. 12, 1948 Great Britain June 9, 1954 OTHER REFERENCES American Handbook ofSynthetic Textiles by Mauersberger, Textile Book Publishers, rst edition, 1952, page 449, Copy in Division 21.

Artificial Fibres by Moncriel, J 0h11 Wiley & Sons, Inc., second edition, 1954, Page 267. 

